Consumer Reports, with one of the most widely
respected product testing laboratories in the world
has just released the results of an extensive test
on oil brands and oil changes, as well as other
issues regarding car care. In the process, the test
demolished much of the conventional wisdom
regarding car lubrication. The two most surprising
results: the frequency with which oil is changed
doesn't matter after the first few oil changes on a
new engine, and the type or brand of oil used can
not be shown to make any difference.

The testers placed freshly rebuilt engines in 75
New York taxis and then ran them for nearly two
years, with each cab racking up 60,000 miles,
placing different brands and weights in different
cars and changing the oil at 3,000 miles in half
the cars and 6,000 in the other half. At the
conclusion of the test period, the engines were
torn down, measured and inspected. The conclusions:
Regardless of brand of oil or weight, no measurable
differences could be observed in engine wear.
Furthermore, there was no difference among cars
which had oil changed at the shorter or longer
interval.

Does this have any bearing on the enthusiast's
car, which is given almost the opposite usage
stored for long periods of time then started and
driven for short distances? The tests suggested
that our type of usage would build up sludge and
varnish, indicating that an annual or semi-annual
oil change is a good idea regardless of how much
mileage the car is driven. But there is little
indication that the brand or weight needs to be
given serious consideration, and synthetic oil has
no discernible advantage over the old stand-bys.
More information on the tests and results can be
obtained from Consumers Union or the July issue of
Consumer Reports available at most libraries.